System and Method for Indicating Wireless Channel Status

ABSTRACT

A method for operating a user equipment includes receiving a first frame on a first channel associated with a first beam identified during a beam failure recovery procedure, and determining that an assumed quasi-co-located relationship exists between the first channel and the first beam, and based thereon, decoding the first frame in accordance with a first reference signal on the first channel and using a first spatial domain receive filter that was used to decode the first beam.

This application is a divisional of U.S. patent application Ser. No.15/987,220, filed on May 23, 2018, entitled “System and Method forIndicating Wireless Channel Status,” which claims the benefit of U.S.Provisional Application No. 62/581,293, filed on Nov. 3, 2017, entitled“System and Method for Indicating Wireless Channel Status,” whichapplication is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a system and method fordigital communications, and, in particular embodiments, to a system andmethod for indicating wireless channel status.

BACKGROUND

One possible deployment scenario for fifth generation (5G) New Radio(NR) system architecture uses high frequency (HF) (6 gigahertz (GHz) andabove, such as millimeter wavelength (mmWave)) operating frequencies toexploit greater available bandwidth and less interference then what isavailable at the congested lower frequencies. However, pathloss is asignificant issue. Beamforming may be used to overcome the highpathloss.

Under certain conditions, a user equipment (UE) device may detect thatall existing communications beam between an evolved NodeB (eNB) and theUE are not working as expected (i.e., there is a beam failure or loss)and there is a need to recover from this condition. However, asignificant amount of channel status information is needed in order tofully maximize the performance a communications beam. The channel statusinformation needs to be shared (sent or otherwise indicated or conveyed)between participating devices. Therefore, there is a need for mechanismsfor indicating channel status information.

SUMMARY

Example embodiments provide a system and method for indicating wirelesschannel status.

In accordance with an example embodiment, a computer implemented methodfor operating a user equipment (UE) is provided. The method includesreceiving, by the UE, a first frame on a first channel associated with afirst beam identified during a beam failure recovery procedure, anddetermining, by the UE, that an assumed quasi-co-located relationshipexists between the first channel and the first beam, and based thereon,decoding, by the UE, the first frame in accordance with a firstreference signal on the first channel and using a first spatial domainreceive filter that was used to decode the first beam.

Optionally, in any of the preceding embodiments, further includesreceiving, by the UE after completion of the beam failure recoveryprocedure, an updated quasi-co-located relationship between the firstchannel and a second beam, receiving, by the UE, a second frame on thefirst channel associated with the second beam, and decoding, by the UE,the second frame in accordance with the first reference signal on thefirst channel and the updated quasi-co-located relationship between thefirst channel and the second beam that enables a second spatial domainreceive filter that was used to decode the second beam to be used todecode the first channel.

Optionally, in any of the preceding embodiments, wherein the first beamand the second beam are the same.

Optionally, in any of the preceding embodiments, wherein the beamfailure recovery procedure completes when a response to a beam failurerecovery request is received.

Optionally, in any of the preceding embodiments, wherein the firstchannel is a physical downlink control channel (PDCCH), and wherein themethod further comprises receiving, by the UE from an access node, aquasi-co-located relationship associated with the PDCCH.

Optionally, in any of the preceding embodiments, wherein the firstchannel is a physical downlink shared channel (PDSCH).

Optionally, in any of the preceding embodiments, further comprisingreceiving, by the UE from an access node, a mapping between transmissionconfiguration indication (TCI) states and a TCI field of a controlframe.

Optionally, in any of the preceding embodiments, further comprisingreceiving, by the UE from an access node, a third frame on a secondchannel, the third frame including scheduling information for the firstframe.

Optionally, in any of the preceding embodiments, wherein decoding thefirst frame is further in accordance with a second reference signalconveyed on the second channel and an additional quasi-co-locatedrelationship between the second channel and the first beam.

Optionally, in any of the preceding embodiments, wherein the secondchannel is a PDCCH.

In accordance with an example embodiment, a computer implemented methodfor operating a UE is provided. The method includes receiving, by theUE, a first data frame on a data channel associated with a first beamidentified during a beam failure recovery procedure, and determining, bythe UE, that an assumed quasi-co-located relationship exists between thedata channel and a control channel, and based thereon, decoding, by theUE, the first data frame in accordance with a reference signal on acontrol channel and using a first spatial domain receive filter that wasused to decode the control channel, wherein the control channel is alsoassociated with the first beam.

Optionally, in any of the preceding embodiments, further includesreceiving, by the UE after completion of the beam failure recoveryprocedure, an updated quasi-co-located relationship between the datachannel and the control channel, receiving, by the UE, a second dataframe on the data channel associated with a second beam, and decoding,by the UE, the second data frame in accordance with the reference signalon the control channel and the updated quasi-co-located relationshipbetween the data channel and the control channel that enables a secondspatial domain receive filter that was used to decode the controlchannel to be used to decode the data channel.

Optionally, in any of the preceding embodiments, wherein the first beamand the second beam are one and the same.

Optionally, in any of the preceding embodiments, wherein the updatedquasi-co-located relationship is received as a TCI state.

Optionally, in any of the preceding embodiments, wherein the TCI stateis received in a higher layer message.

Optionally, in any of the preceding embodiments, wherein the datachannel is a PDSCH and the control channel is a PDCCH.

In accordance with an example embodiment, a UE is provided. The UEincludes a memory storage comprising instructions, and one or moreprocessors in communication with the memory storage. The one or moreprocessors execute the instructions to receive a first frame on a firstchannel associated with a first beam identified during a beam failurerecovery procedure, and determine that an assumed quasi-co-locatedrelationship exists between the first channel and the first beam, andbased thereon, decode the first frame in accordance with a firstreference signal on the first channel and using a first spatial domainreceive filter that was used to decode the first beam.

Optionally, in any of the preceding embodiments, wherein the one or moreprocessors further execute the instructions to: receive, aftercompletion of the beam failure recovery procedure, an updatedquasi-co-located relationship between the first channel and a secondbeam, receive a second frame on the first channel associated with thesecond beam, and decode the second frame in accordance with the firstreference signal on the first channel and the updated quasi-co-locatedrelationship between the first channel and the second beam that enablesa second spatial domain receive filter that was used to decode thesecond beam to be used to decode the first channel.

Optionally, in any of the preceding embodiments, wherein the firstchannel is a PDSCH, and wherein the one or more processors furtherexecute the instructions to: receive, from an access node, a mappingbetween TCI states and a TCI field of a control frame.

Optionally, in any of the preceding embodiments, wherein the one or moreprocessors further execute the instructions to: receive, from an accessnode, a third frame on a second channel, the third frame includingscheduling information for the first frame.

In accordance with an example embodiment, a UE includes a memory storagecomprising instructions, and one or more processors in communicationwith the memory storage. The one or more processors execute theinstructions to receive a first data frame on a data channel associatedwith a first beam identified during a beam failure recovery procedure,and determine that an assumed quasi-co-located relationship existsbetween the data channel and a control channel, and based thereon,decode the first data frame in accordance with a reference signal on acontrol channel and using a first spatial domain receive filter that wasused to decode the control channel, wherein the control channel is alsoassociated with the first beam.

Optionally, in any of the preceding embodiments, wherein the one or moreprocessors further execute the instructions to: receive, aftercompletion of the beam failure recovery procedure, an updatedquasi-co-located relationship between the data channel and the controlchannel, receive a second data frame on the data channel associated witha second beam, and decode the second data frame in accordance with thereference signal on the control channel and the updated quasi-co-locatedrelationship between the data channel and the control channel thatenables a second spatial domain receive filter that was used to decodethe control channel to be used to decode the data channel.

Optionally, in any of the preceding embodiments, wherein the updatedquasi-co-located relationship is received as a TCI state.

Practice of the foregoing embodiments enables a UE, after beam failurerecovery, to determine which reference signal to use with data orcontrol channels. The embodiments also help to reduce the signalingoverhead associated with updating channel status information after beamfailure recovery, thereby improving communications system performance.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates an example wireless communications system accordingto example embodiments described herein;

FIG. 2 illustrates a communications system highlighting an examplechannel structure between an access node 205 and a UE according toexample embodiments described herein;

FIG. 3 illustrates a wireless communications system highlighting beamfailure and beam failure recovery according to example embodimentsdescribed herein;

FIG. 4A illustrates a diagram of example beams for WBRS and CSI-RSaccording to example embodiments described herein;

FIG. 4B illustrates a graphical representation of two precoders that arespatially QCL'ed according to example embodiments described herein;

FIG. 5 illustrates a flow diagram of example operations occurring in aUE that has experienced beam failure while operating in a QCLenvironment and recovers from the beam failure and uses QCLconfiguration of a new beam according to example embodiments describedherein;

FIG. 6A illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame on a PDCCH according to example embodimentsdescribed herein;

FIG. 6B illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame, where a TCI field is or is not included in aDCI that schedules a PDSCH according to example embodiments describedherein;

FIG. 6C illustrates a flow diagram of example operations occurring in anaccess node updating TCI states according to example embodimentsdescribed herein;

FIG. 6D illustrates a flow diagram of example operations occurring in aUE participating in a DCI selection procedure, where a TCI field ispresent in the DCI prior to beam failure but is not present in the DCIafter beam failure according to example embodiments described herein;

FIG. 6E illustrates a flow diagram of example operations occurring in aUE participating in a DCI selection procedure, where a TCI field is notpresent in the DCI prior to beam failure but is present in the DCI afterbeam failure according to example embodiments described herein;

FIG. 7 illustrates a flow diagram of example operations occurring in aUE that has experienced beam failure while operating in a QCLenvironment and recovers from the beam failure and does not use QCLconfiguration of a new beam according to example embodiments describedherein;

FIG. 8A illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame on a PDCCH according to example embodimentsdescribed herein;

FIG. 8B illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame on a PDSCH, where a TCI field is present in aDCI that schedules the PDSCH according to example embodiments describedherein;

FIG. 8C illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame on a PDSCH, where a TCI field is not presentin a DCI that schedules the PDSCH according to example embodimentsdescribed herein;

FIG. 8D illustrates a flow diagram of example operations occurring in aUE participating in a beam failure detection, a beam failure recovery,and a decoding of a frame on a PDSCH, where a TCI field is present in aDCI that schedules the PDSCH and preset values are used according toexample embodiments described herein;

FIG. 9 illustrates an example communication system according to exampleembodiments described herein;

FIGS. 10A and 10B illustrate example devices that may implement themethods and teachings according to this disclosure; and

FIG. 11 is a block diagram of a computing system that may be used forimplementing the devices and methods disclosed herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the disclosed embodiments are discussed indetail below. It should be appreciated, however, that the presentdisclosure provides many applicable inventive concepts that can beembodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the embodiments, and do not limit the scope of the disclosure.

FIG. 1 illustrates an example wireless communications system 100.Communications system wo includes an access node 105 serving a userequipment (UE) 115. In a first operating mode, communications to andfrom UE 115 pass through access node 105. In a second operating mode,communications to and from UE 115 do not pass through access node 105,however, access node 105 typically allocates resources used by UE 115 tocommunicate. Access nodes may also be commonly referred to as evolvedNodeBs (eNBs), base stations, NodeBs, master eNBs (MeNBs), secondaryeNBs (SeNBs), next generation (NG) NodeBs (gNBs), master gNBs (MgNBs),secondary gNBs (SgNBs), remote radio heads, access points, and the like,while UEs may also be commonly referred to as mobiles, mobile stations,terminals, subscribers, users, stations, and the like. A transmissionpoint (TP) may be used to refer to any network entity capable oftransmitting. Similarly, transmission-reception points (TRP) is anetwork entity that is capable of both transmitting and receiving, andcommonly refer to access nodes, eNBs, gNBs, base stations, NodeBs,MeNBs, SeNBs, MgNBs, SgNBs, remote radio heads (RRHs), access points. Insome situations, UEs (and similar devices) may also be operating asTRPs.

While it is understood that communications systems may employ multipleaccess nodes capable of communicating with a number of UEs, only oneaccess node and one UE are illustrated for simplicity.

As discussed previously, pathloss in communications systems operating athigh frequency (HF) (6 gigahertz (GHz) and above, such as millimeterwavelength (mmWave)) operating frequencies, is high, and beamforming maybe used to overcome the high pathloss. As shown in FIG. 1 , both accessnode 105 and UE 115 communicate using beamformed transmissions andreceptions. As an example access node 105 communicates using a pluralityof communications beams, including beams no and 112, while UE 115communicates using a plurality of communications beams, including beams120 and 122.

A beam may be a pre-defined set of beamforming weights in the context ofcodebook-based precoding or a dynamically defined set of beamformingweights in the context of non-codebook based precoding (e.g.,Eigen-based beamforming (EBB)). A beam may also be a pre-defined set ofphase shift preprocessors combining signals from the antenna array inthe radio frequency (RF) domain. It should be appreciated that a UE mayrely on codebook-based precoding to transmit uplink signals and receivedownlink signals, while a TRP may rely on non-codebook based precodingto form certain radiation patterns to transmit downlink signals orreceive uplink signals.

FIG. 2 illustrates a communications system 200 highlighting an examplechannel structure between an access node 205 and a UE 210. In abi-directional communications implementation, there is a downlinkchannel 220 and an uplink channel 230 between access node 205 and UE210. Downlink channel 220 and uplink channel 230 may each include aplurality of unidirectional channels. As shown in FIG. 2 , downlinkchannel 220 includes a physical downlink shared channel (PDSCH) 222 anda physical downlink control channel (PDCCH) 224 among others, whileuplink channel 230 includes a physical uplink control channel (PUCCH)232 and a physical uplink shared channel (PUSCH) 234 among others.

FIG. 3 illustrates a wireless communications system 300 highlightingbeam failure and beam failure recovery. Communications system 300includes an access node 305 serving a UE 315. As shown in FIG. 3 , bothaccess node 305 and UE 315 communicate using beamformed transmissionsand receptions. As an example access node 305 communicates using aplurality of communications beams, including beams 310 and 312, while UE315 communicates using a plurality of communications beams, includingbeams 320 and 322.

Initially, access node 305 and UE 315 are communicating through beampair link (BPL) 325, which comprises beams 310 and 322. However, due toblockage or UE mobility, BPL 325 fails. UE 315 detects a candidate beam312 from access node 305 to replace failed beam 310, for example. UE 315initiates beam failure recovery by sending a beam failure recoveryrequest (BFRQ) to access node 305. Upon completion of the beam failurerecovery, BPL 330 is established (comprising beams 312 and 320).

When two or more reference signals, data signals or resources arerelated in such a way that the two or more reference signals, datasignals or resources may be viewed as possessing similarcharacteristics, they are said to possess a quasi co-located (QCL)relationship. QCL relationships may refer to time, frequency, code, orspatial relationships between two or more reference signals, datasignals, or resources, while spatial QCL refers to only spatialrelationships between two or more reference signals, data signals, orresources. The spatial QCL information may include associations betweensignals and resources, such as CSI-RS resources and wideband referencesignals (WBRS), or associations between individual WBRSs, orassociations between CSI-RS resources and beamformed random accesschannels (BRACHs). As an example, in a one to one association, eachCSI-RS signal is associated with one WBRS such that the transmitprecoder for the CSI-RS signal is the same as a transmit precoder forthe WBRS. As another example, each CSI-RS signal is associated with oneWBRS such that the transmit precoder for the CSI-RS signal is the sameas a transmit precoder for the WBRS. As another example, a first WBRS isassociated with a second WBRS such that the transmit precoder for thesecond WBRS is the same as that for the first WBRS. It is possible thatmultiple CSI-RS signals are associated with a single WBRS, and viceversa. The spatial QCL information may be stored in tabular form or in amemory of a device. The spatial QCL information includes associationsbetween CSI-RS and WBRSs. The spatial QCL information may be used by theUE to determine CSI-RS beam indices from WBRS beam indices, and viceversa, for example. As an example, in a one-to-one association, eachCSI-RS signal is associated with one WBRS. It is possible that multipleCSI-RS signals are associated with a single WBRS, and vice versa.

FIG. 4A illustrates a diagram 400 of example beams for WBRS and CSI-RS.As shown in FIG. 4A, a precoder for an example WBRS has beam footprint405, while precoders for example CSI-RS1, CSI-RS2, CSI-RS3, and CSI-RS4have beam footprints 410, 412, 414, and 416, respectively.

FIG. 4B illustrates a graphical representation 450 of two precoders thatare spatially QCL'ed. A first beam pattern 455 represents a precoder fora first signal and a second beam pattern 460 represents a precoder for asecond signal. The beam patterns overlap because the two precoders areidentical (or substantially identical).

At the Third Generation Partnership Project (3GPP) RAN1 AdHoc NR #3meeting, mechanisms for sharing QCL information of downlink physicalchannels were discussed. Some agreements were made, including:

-   -   A UE is configured using radio resource control (RRC) messaging        with a list of up to M candidate transmission configuration        indication (TCI) states at least for the purposes of sharing QCL        information;        -   Whether M is equal to or larger than 2^(N) is for further            study, where N is the size of a downlink control            information (DCI) field for PDSCH;        -   Mapping between the candidate TCI states to states described            by N bit DCI field PDSCH is for further study;        -   Each TCI state may be configured with at least one reference            signal (RS) set;        -   Each identifier (ID), with details of the ID for further            study, for downlink RS at least for the purpose of spatial            QCL in an RS set may refer to one of the following downlink            RS types: synchronization signal block (SSB), periodic            channel state information reference signal (CSI-RS),            aperiodic CSI-RS, or semi-persistent CSI-RS;        -   Other RS, such as tracking reference signal (TRS),            phase-tracking reference signal (PTRS), in an RS set            depending on an outcome of discussions of QCL agenda item;        -   Mechanisms to initialize or update the ID of a downlink RS            or RSs in the RS set used for (at least) spatial QCL            purposes are for further study            -   At least the two following mechanisms are for further                study, (1) explicit signaling to the UE of the downlink                RS(s) ID and corresponding TCI state, and (2) implicit                association of the downlink RS(s) ID to a TCI state                based on measurements by the UE;            -   Mechanisms used for different RS types are for further                study;        -   Whether or not a TCI state includes other parameter(s),            e.g., for PDSCH rate matching purposes, are for further            study; and        -   Value of N, where N is at most three bits, is for further            study. It is noted that additional details on the            specification of more than one demodulation reference signal            (DMRS) port group and more than one RS set per TCI is to be            completed.

Also agreed were:

-   -   The QCL configuration for PDCCH contains the information that        provides a reference to a TCI state, with        -   Alternate 1: the QCL configuration or representation thereof            is on a per CORESET basis, with the UE applying the QCL            assumption to the associated CORESET monitoring occasions.            All search space(s) within the CORESET utilize the same QCL;        -   Alternate 2: The QCL configuration or representation thereof            is on a per search space basis, with the UE applying the QCL            assumption on an associated search space. Potentially            meaning that in a situation where there are multiple search            spaces with a CORESET, the UE may be configured with            different QCL assumptions for different search spaces; It is            noted that the sharing of QCL configuration is performed            using RRC or RRC and medium access control (MAC) control            element (CE). Sharing of QCL configuration by DCI is for            further study. It is also noted that the above assumptions            are provided as input to the control channel discussion.

Also agreed were:

-   -   For sharing of QCL configuration of the PDSCH:        -   When TCI states are used for sharing of QCL configuration,            the UE receives an N-bit TCI field in DCI,            -   The UE assumes that the PDSCH DMRS is QCL with the                downlink RS(s) in the RS set corresponding to the                signaled TCI state. For further study, whether or not a                QCL type is configured, and configuration details.        -   Whether or not the TCI field is always present in a given            downlink-related DCI is for further study;        -   Whether or not the TCI field is in the same DCI as that            containing the PDSCH scheduling assignment is for further            study;    -   For further study, timing between when the UE receives a QCL        configuration or representation thereof and a first time that        the QCL assumption may be applied for demodulation of PDSCH or        PDCCH.

At the 3GPP RAN1 #90bis meeting, mechanisms on sharing of QCLconfiguration for downlink physical channels were discussed, and thefollowing agreements were made:

-   -   Initialization or update of the identifier of a downlink RS(s)        in the RS set used at least for spatial QCL purposes is        performed at least via explicit signaling. Explicit signaling        using RRC or RRC+MAC CE are supported.    -   Implicit update via an implicit association of the downlink RS        ID(s) to a TCI state based on measurements by a UE are for        further study.

Also agreed were:

-   -   In the situation when at least spatial QCL is configured or        conveyed, higher layer UE-specific configuration of whether or        not the TCI field is present in downlink-related DCI is        supported.        -   If the TCI field is not present, no dynamic conveyance of            QCL parameters for PDSCH is provided in            downlink-related DCI. For PDSCH, a UE applies higher-layer            signaling of QCL parameters or representation thereof for            determining QCL parameters (details are for further study)            except for the situation of beam management without            beam-related information where no spatial QCL parameters are            configured using higher layer signaling.        -   If the TCI field is present,            -   The TCI field is always present in the associated DCI                for PDSCH scheduling, irrespective of same-slot                scheduling or cross-slot scheduling.            -   If the scheduling offset is less than a threshold K,                PDSCH uses a pre-configured, pre-defined, or rule-based                spatial assumption (details are for further study). Also                for further study, the other QCL parameters are still                obtained from the N-bit TCI state field of the DCI, and                how to update pre-configured or pre-defined spatial                assumption (if applicable). The threshold K may be based                on UE capability only if multiple candidate values of K                are supported.            -   If the scheduling offset is greater than or equal to a                threshold K, PDSCH uses the beam (a spatial QCL                parameter) conveyed by the N-bit TCI field in the                assignment DCI.

The proposed candidate solutions should consider below and above 6 GHzdownlink beam related operation with and without beam information ordownlink beam management with and without beam information.

It is noted this does not apply to the situation of beam managementwithout beam-related information.

Example operations based on the 3GPP RAN1 AdHoc NR #3 meeting and the3GPP RAN1 #90bis meeting agreement include:

-   -   An access node maintains a list of up to M candidate TCI states        at least for the purposes of sharing of QCL configuration and        configures it to a UE. Each TCI state can be configured for one        RS set;    -   Out of the up to M candidate TCI states, up to 2^(N) states are        mapped to an N bit DCI for PDSCH, with M being equal to or        greater than 2^(N);    -   For a PDSCH transmission, the access node conveys information        about a downlink RS(s) that is QCL'ed with the DMRS of the PDSCH        by TCI state in the DCI of a PDCCH that schedules the PDSCH.

It is noted that as used in the discussion presented herein, the termQCL may generally refer to both QCL and spatial QCL. In circumstanceswhere such usage would lead to confusion, spatial QCL will be used asneeded.

However, when a beam failure occurs, the channel quality of currentlyused beams is significantly deteriorated. Hence, it is highly likelythat the channel quality of downlink RSs configured in TCI states arealso deteriorated, and thus, no downlink RSs in the TCI states may beused for the conveying of the QCL configuration of PDCCH or PDSCH.Therefore, once a beam failure occurs, there is no proper way forconveying the QCL configuration for PDCCH or PDSCH after beam failurerecovery until there is an update of the ID of a downlink RS(s) in theRS set used at least for spatial QCL purposes is completed.

As related to the conveying of the QCL configuration for PDCCH, theconveying of the QCL configuration is performed using RRC or RRC and MACCE. Potential scenarios include:

-   -   A first downlink RS (such as a synchronization signal block; a        periodic, aperiodic, or semi-persistent CSI-RS; and so on) is        configured to be QCL'ed with a DMRS for PDCCH for a UE, and is        used as a current beam;    -   A beam failure occurs such that the channel quality of the first        downlink RS is severely deteriorated;    -   A second downlink RS is selected as a new beam during a beam        failure recovery procedure;    -   After beam failure recovery and before RRC or RRC and MAC CE        signaling that the second downlink RS is configured to be QCL'ed        with the DMRS for PDCCH, the UE considers the first downlink RS        to be QCL'ed with the DMRS for PDCCH, whose channel quality is        too poor to be used.

As related to the conveying of the QCL configuration for PDSCH, the TCIstates and their mapping to DCI is RRC configured, and a TCI field ispresent in a DCI of a PDCCH that schedules a PDSCH. Potential scenariosinclude:

-   -   An access node configures a first downlink RS (such as a        synchronization signal block; a periodic, aperiodic, or        semi-persistent CSI-RS; and so on) to be QCL'ed with a DMRS for        PDSCH for a UE, and the first downlink RS is used as a current        beam;    -   A beam failure occurs such that the channel quality of the first        downlink RS is severely deteriorated;    -   A second downlink RS is selected as a new beam during a beam        failure recovery procedure, but the second downlink RS is not        listed in the TCI states;    -   After beam failure recovery and before the second downlink RS is        listed as one of the TCI states and mapped to the TCI field in        the DCI, the access node cannot convey information about the        second downlink RS in the TCI field of the DCI as a QCL        configuration for PDSCH.

According to an example embodiment, techniques for operating in a QCLenvironment after beam failure recovery but prior to TCI states relatedto spatial QCL purposes updates are complete are provided. Utilizing QCLinformation after beam failure recovery but before TCI states related tospatial QCL purposes are updated may lead to degraded performance due tooutdated or incorrect QCL information.

According to a first example embodiment, after beam failure recovery, aselected new beam is used for the QCL configuration for PDCCH or PDSCH.In other words, the QCL configuration associated with the selected newbeam is used by the UE. The QCL configuration associated with theselected new beam may be used by the UE until updates to TCI states arereceived, for example.

FIG. 5 illustrates a flow diagram of example operations 500 occurring ina UE that has experienced beam failure while operating in a QCLenvironment and recovers from the beam failure and uses QCLconfiguration of a new beam. Operations 500 may be indicative ofoperations occurring in a UE as the UE experiences beam failure whileoperating in a QCL environment and recovers from the beam failure anduses QCL configuration of a new beam selected during beam failurerecovery.

Operations 500 begin with the UE completing beam failure recovery (block505). Completion of the beam failure recovery includes the reception ofa response to the BFRQ sent by the UE to initiate beam failure recovery.The response to the BFRQ implicitly includes information related to anew beam selected to replace the beam that failed. As an example, theresponse to the BFRQ has a QCL relationship with the selected new beam,and hence, the UE is able to infer information about the selected newbeam from the response to the BFRQ and its QCL relationship with theselected new beam. Alternatively, the response to the BFRQ explicitlyincludes information related to the new beam selected to replace thebeam that failed. Hence, the UE is able to obtain information about theselected new beam directly from the response to the BFRQ. The UE decodesany received transmissions by using an assumed (or inferred) QCLrelationship between the selected new beam and a downlink RS of PDCCH orPDSCH (block 507). In other words, the UE decodes a receivedtransmission by assuming (or inferring) that there exists a QCLrelationship between the selected new beam and a downlink RS, such as aDMRS, of a PDCCH or PDSCH, before any updated QCL configuration isreceived. For example, the UE uses the same spatial domain receivefilter for receiving and decoding the DMRS of the PDCCH or PDSCH as forreceiving and decoding the selected new beam. The UE continues to usethe assumed QCL relationship until an update is received. In general, anupdate is received some time after the completion of the beam failurerecovery process, and until the update is received, the UE uses theassumed QCL relationship to receive and decode received transmissions.The UE receives an updated QCL configuration (block 509). After thecompletion of the beam failure recovery process, updates to the QCLconfiguration are signaled, by the access node, for example. The UE usesthe updated QCL configuration as the QCL configuration of the PDCCH orPDSCH to decode received transmissions (block 511). It is noted that theupdated QCL configuration may specify a QCL relationship that isdifferent from the assumed QCL relationship. As an example, the updatedQCL configuration may specify a beam, that is different from theselected new beam, having a QCL relationship with the downlink RS. Asanother example, the updated QCL configuration may specify more than onebeam, with one beam being the selected new beam and one or more otherbeams, having a QCL relationship with the downlink RS.

As an illustrative example, after beam failure recovery, a QCLrelationship is assumed between the selected new beam and a downlink RSof a PDCCH or PDSCH. A TCI table is updated to include the selected newbeam. If a TCI field is present in the DCI, a mapping between TCI statesand the TCI field in the DCI is updated in such a way that the TCI fieldconveys information about the selected new beam. As another illustrativeexample, after beam failure recovery, the UE assumes that, for decodingdata transmissions, the QCL relationship between control transmissionson the PDCCH and a RS of the PDCCH also applies to data transmissions onthe PDSCH and a RS of the PDSCH until an update to the TCI states isreceived.

In a first embodiment of the first example embodiment, a beam failuredetection, a beam failure recovery, and a decoding of a frame on a PDCCHprocess may be as follows:

-   -   A UE receives a first information from an access node related to        a QCL configuration for PDCCH, wherein the QCL configuration for        PDCCH includes a second information that a first RS is spatially        QCL'ed with a DMRS of PDCCH;    -   The UE detects a beam failure;    -   The UE identifies a second RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a beam failure recovery response (BFRP) from the        access node;    -   The UE receives a frame on a PDCCH, after beam failure recovery;    -   The UE decodes the frame by assuming that a DMRS of the PDCCH is        QCL'ed (i.e., has a QCL relationship) with the second RS.

It is noted that the first RS may be from a first set of TCI states. Itis noted that the first information may be shared by RRC or RRC and MACCE signaling. It is noted that the BFRQ may carry information related tothe second RS. It is noted that the BFRP may carry information relatedto the second RS. It is noted that the UE may decode the BFRP byassuming that a DMRS of the PDCCH is QCL'ed with the second RS. It isnoted that the PDCCH may carry a TCI field and the TCI field may be setto a predetermined value. The predetermined value may be set to zero.The predetermined value may be set to a maximum value that the TCI fieldis capable of representing, e.g., seven if the TCI field is three bitslong, three if the TCI field is two bits long, etc. The predeterminedvalue may be set to a value that no specific RS is mapped to in the TCIfield. As an example, if the length of the TCI field is 2 bits long,implying that there are 4 states that the TCI field is capable ofrepresenting. If there are only 2 states mapped to the TCI field, e.g.,state o and state 1, then states 2 and 3 may be the predeterminedvalues.

The beam failure detection, beam failure recovery, and decoding of aframe on a PDCCH process may also include:

-   -   The UE receiving signaling that updates a QCL configuration for        PDCCH, where the QCL configuration for PDCCH includes        information that a third RS is spatially QCL'ed with a DMRS of        PDCCH;    -   The UE receives a second frame on PDCCH, after beam failure        recovery;    -   The UE decodes the second frame by assuming that a DMRS of the        PDCCH is QCL'ed with the third RS from a second set of TCI        states.

It is noted that the second RS may be from the second set of TCI states.It is also noted that the third RS and the second RS may be one and thesame.

FIG. 6A illustrates a flow diagram of example operations 600 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame on a PDCCH.

Operations 600 begin with the UE completing a beam failure recoveryprocedure (block 602). Part of the beam failure recovery procedureincludes the UE selecting a new beam or receiving information about thenew beam. The UE receives a frame on a PDCCH (block 604). The UE decodesthe frame (block 606). The UE decodes the frame by assuming that a DMRSof the PDCCH is QCL'ed with the new beam, for example.

In a second embodiment of the first example embodiment, a beam failuredetection, a beam failure recovery, and a decoding of a frame on a PDSCHprocess, where a TCI field is included in a DCI that schedules thePDSCH, may be as follows:

-   -   A UE receives an information from an access node regarding a        mapping between TCI states and the TCI field in the DCI;    -   The UE detects a beam failure;    -   The UE identifies a first RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a first data frame on PDSCH;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with the first RS.

It is noted that the UE may further receive a DCI that schedules thefirst data frame, where the DCI carries a TCI field and the TCI field isset to a predetermined value. The predetermined value may be set tozero. The predetermined value may be set to a maximum value that the TCIfield is capable of representing, e.g., seven if the TCI field is threebits long, three if the TCI field is two bits long, etc. Thepredetermined value may be set to a value that no specific RS is mappedto in the TCI field. As an example, if the length of the TCI field is 2bits long, implying that there are 4 states that the TCI field iscapable of representing. If there are only 2 states mapped to the TCIfield, e.g., state o and state 1, then states 2 and 3 may be thepredetermined values.

It is noted that the UE may decode the BFRP by assuming that a DMRS of aPDCCH is QCL'ed with the first RS, the PDCCH carrying the BFRP, forexample. It is noted that the BFRP may carry a TCI field and that theTCI field is set to a first value. The UE may assign the first RS for aRS for spatial QCL configuration corresponding to the first value of theTCI field. It is noted that the UE may further receive a DCI thatschedules the first data frame, where the DCI carries a TCI field andthe TCI field is set to the first value. It is noted that the TCI fieldin the DCI that schedules the first data frame may reassign the firstRS. In such a situation, the TCI field in the DCI is set to a firstvalue and the UE may assign the first RS as a RS for spatial QCLconfiguration corresponding to the first value of the TCI field.

In an additional second embodiment of the first example embodiment, abeam failure detection, a beam failure recovery, and a decoding of aframe on a PDSCH process, where a TCI field is included in a DCI thatschedules the PDSCH, may be as follows:

-   -   A UE receives an information from an access node regarding a        mapping between TCI states and the TCI field in the DCI;    -   The UE detects a beam failure;    -   The UE identifies a first RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a first control frame that schedules a first        data frame, where the first control frame is carried on a PDCCH        and the first data frame is carried on a PDSCH;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with a RS that a DMRS of the PDCCH is QCL'ed        with.

It is noted that the DMRS of the PDSCH may be QCL'ed with the DMRS ofthe PDCCH.

In a third embodiment of the first example embodiment, a beam failuredetection, a beam failure recovery, and a decoding of a frame on a PDSCHprocess, where a TCI field is not included in a DCI that schedules thePDSCH, may be as follows:

-   -   A UE determines a first RS that is QCL'ed with a DMRS for PDSCH        decoding;    -   The UE detects a beam failure;    -   The UE identifies a second RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a first data frame on PDSCH;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with the second RS.

FIG. 6B illustrates a flow diagram of example operations 615 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame, where a TCI field is or is notincluded in a DCI that schedules a PDSCH.

Operations 615 begin with the UE optionally receiving informationregarding a mapping between TCI states and a TCI field in a DCI (block617). The UE completes a beam failure recovery procedure (block 619).Part of the beam failure recovery procedure includes the UE selecting anew beam or receiving information about the new beam. The UE may receivea control frame on a PDCCH (block 621). The UE receives a data frame ona PDSCH (block 623). The UE decodes the data frame (block 625). The UEdecodes the data frame by assuming that a DMRS of the PDSCH is QCL'edwith the new beam, for example. The UE decodes the data frame byassuming that a DMRS of the PDSCH is QCL'ed with a RS that a DMRS of thePDCCH is QCL'ed with, for example.

In an additional third embodiment of the first example embodiment, abeam failure detection, a beam failure recovery, and a decoding of aframe on a PDSCH process, may be as follows:

-   -   The UE detects a beam failure;    -   The UE identifies a first RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node, where the BFRP        schedules a first data frame transmission on a PDSCH;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with the first RS.

It is noted that the BFRP may carry a TCI field that is set to a firstvalue, and that the UE assumes the first RS as the RS for QCLconfiguration corresponding to the first value of the TCI field. It isnoted that the BRFP may carry a TCI field that is set to a predeterminedvalue and that the predetermined value may be set to one of a variety ofpredetermined values, such as zero, a maximum value, not assigned, andso forth. It is noted that the DMRS of the BFRP and the PDSCH may beQCL'ed with the same RS.

In a fourth embodiment of the first example embodiment, a TCI stateupdate procedure may be as follows:

-   -   An access node maintains a TCI table that includes a first group        of states where each of the states represents a RS that may be        used for spatial QCL configuration;    -   The access node receives a BFRQ from a UE;    -   The access node identifies a first RS as a new beam for beam        failure recovery with the UE;    -   The access node sends a BFRP to the UE;    -   The access node updates the TCI table, where the updated TCI        table includes a second group of states where each of the states        represents a RS that may be used for spatial QCL configuration,        and one state from the second group of states corresponds to the        first RS.

It is noted that the number of states in the second group of states maybe one. It is noted that none of the states in the first group of statesmay correspond to the first RS. It is noted that the access node mayfurther update a mapping between TCI states and the TCI field in theDCI, where a third group of states from the second group of states ismapped to each value of the TCI field in the DCI, and one state from thethird group of states corresponds to the first RS. The value of the TCIfield in the DCI that corresponds to the first RS may be set to zero.

FIG. 6C illustrates a flow diagram of example operations 630 occurringin an access node updating TCI states.

Operations 630 begin with the access node maintaining a TCI table (block632). The TCI table includes a first group of states, where each staterepresents a RS that may be used for spatial QCL configuration, forexample. The access node completes beam failure recovery procedure(block 634). Part of the beam failure recovery procedure may include theaccess node identifying a first RS as a new beam for the beam failurerecovery procedure. The access node updates the TCI table (block 636).The updated TCI table includes a second group of states where each ofthe states represents a RS that may be used for spatial QCLconfiguration, and one state from the second group of states correspondsto the first RS (the new beam), for example.

In a fifth embodiment of the first example embodiment, a DCI selectionprocedure, where a TCI field is present prior to beam failure but is notpresent after beam failure, may be as follows:

-   -   A UE is configured that a TCI field is present in a        downlink-related DCI;    -   The UE detects a beam failure;    -   The UE identifies a first RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;—With beam recovery        successful, the UE assumes that the TCI field is not present in        the downlink-related DCI until the UE receives a QCL        configuration from the access node.

It is noted that the UE may further receive a first data frame on aPDSCH. The UE may decode the first data frame by assuming that a DMRS ofthe PDSCH is QCL'ed with the first RS.

FIG. 6D illustrates a flow diagram of example operations 640 occurringin a UE participating in a DCI selection procedure, where a TCI field ispresent in the DCI prior to beam failure but is not present in the DCIafter beam failure.

Operations 640 begin with the UE being configured that a TCI field ispresent in downlink-related DCI (block 642). The UE completes beamfailure recovery procedure (block 644). Part of the beam failurerecovery procedure includes the UE selecting a new beam or receivinginformation about the new beam. The UE operates under an assumption thatthe TCI field is not present in downlink-related DCI until QCLconfiguration is received from an access node (block 646).

In a sixth embodiment of the first example embodiment, a DCI selectionprocedure, where a TCI field is not present prior to beam failure but ispresent after beam failure, may be as follows:

-   -   A UE is configured that a TCI field is not present in a        downlink-related DCI;    -   The UE detects a beam failure;    -   The UE identifies a first RS as a new beam for beam failure        recovery;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;—With beam recovery        successful, the UE assumes that the TCI field is present in the        downlink-related DCI until the UE receives a QCL configuration        from the access node.

It is noted that the UE may further receive information from the accessnode regarding a mapping between TCI states and the TCI field in the DCIbefore the beam failure occurs. After the beam failure occurs, the UEmay receive a first DCI that schedules a first data frame on a firstPDSCH, where the first DCI includes a TCI field set to a first value.The UE may decode the first data frame by assuming that a DMRS of thePDSCH is QCL'ed with the first RS. It is noted that the UE may assignthe first RS for a RS for spatial QCL configuration corresponding to thefirst value of the TCI field.

FIG. 6E illustrates a flow diagram of example operations 650 occurringin a UE participating in a DCI selection procedure, where a TCI field isnot present in the DCI prior to beam failure but is present in the DCIafter beam failure.

Operations 650 begin with the UE being configured that a TCI field isnot present in downlink-related DCI (block 652). The UE completes beamfailure recovery procedure (block 654). Part of the beam failurerecovery procedure includes the UE selecting a new beam or receivinginformation about the new beam. The UE operates under an assumption thatthe TCI field is present in downlink-related DCI until a QCLconfiguration is received from an access node (block 656).

According to a second example embodiment, after beam failure recovery,no QCL configuration is considered until TCI states related to spatialQCL purposes are updated. In other words, the UE uses only RSsassociated with PDCCH or PDSCH for detection or decoding purposes. TheUE uses a DMRS associated with PDCCH or PDSCH for detection or decodingpurposes until updates to TCI states are received, for example.

FIG. 7 illustrates a flow diagram of example operations 700 occurring ina UE that has experienced beam failure while operating in a QCLenvironment and recovers from the beam failure and does not use QCLconfiguration of a new beam. Operations 700 may be indicative ofoperations occurring in a UE as the UE experiences beam failure whileoperating in a QCL environment and recovers from the beam failure anddoes not use QCL configuration of a new beam selected during beamfailure recovery.

Operations 700 begin with the UE completing beam failure recovery (block705). After completing beam failure recovery, the UE may assume thatthere is no downlink RS configured for QCL relation for PDCCH or PDSCH(block 707). Hence, when the UE receives a PDCCH or PDSCH, the UE mayonly use a DMRS of the PDCCH or PDSCH for detection or decoding of thePDCCH or PDSCH. The UE receives updates to TCI states related to spatialQCL purposes (block 709). The UE uses the updated QCL configuration forsubsequent for subsequent PDCCH or PDSCH detection or decoding (block711). As an example, the UE detects or decodes a PDCCH or PDSCH byassuming that a DMRS of the PDCCH or PDSCH is QCL'ed with a new beamselected in beam failure recovery and uses the new beam (or a RS carriedon the new beam) to assist in the decoding.

As an illustrative example, after beam failure recovery completes, theUE assumes that there is no downlink RS configured for QCL relation forPDCCH or PDSCH. Therefore, when the UE receives a PDCCH or PDSCH, the UEmay only rely upon a DMRS of the PDCCH or PDSCH for detection ordecoding of the PDCCH or PDSCH. When the TCI states related to spatialQCL are updated, the UE may resume using QCL configuration based ondownlink signaling.

In a first embodiment of the second example embodiment, a PDCCH framedecoding process may be as follows:

-   -   A UE receives a first information from an access node regarding        a QCL configuration for PDCCH, where the QCL configuration for        PDCCH includes a second information that a first RS is spatially        QCL'ed with a DMRS of PDCCH;    -   The UE detects a beam failure;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a frame on a PDCCH, after beam failure recovery;    -   The UE decodes the frame by assuming that a DMRS of the PDCCH is        not QCL'ed with the first RS. In other words, the DMRS of the        PDCCH does not have a QCL relationship with the first RS.

It is noted that the QCL configuration may be conveyed via RRC or RRCand MAC CE signaling. It is noted that the first RS may be from a firstset of TCI states. It is noted that the PDCCH may carry a TCI field andthe TCI field is set to a predetermined value. The predetermined valuemay be set to zero. The predetermined value may be set to a maximumvalue that the TCI field is capable of representing, e.g., seven if theTCI field is three bits long, three if the TCI field is two bits long,etc. The predetermined value may be set to a value that no specific RSis mapped to in the TCI field. As an example, if the length of the TCIfield is 2 bits long, implying that there are 4 states that the TCIfield is capable of representing. If there are only 2 states mapped tothe TCI field, e.g., state o and state 1, then states 2 and 3 may be thepredetermined values. It is noted that the BFRP may carry a TCI fieldand the TCI field is set to a predetermined value. It is noted that theTCI field in the BFRP may be set to a predetermined value as describedabove.

The PDCCH frame decoding process may also include:

-   -   The UE receives signaling that updates a QCL configuration for        PDCCH, where the QCL configuration for PDCCH includes an        information that a second RS from a second set of TCI states is        spatially QCL'ed with a DMRS of PDCCH;    -   The UE receives a second frame on the PDCCH, after beam failure        recovery;    -   The UE decodes the second frame by assuming that a DMRS of the        PDCCH is QCL'ed with the second RS from the second set of TCI        states.

FIG. 8A illustrates a flow diagram of example operations 800 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame on a PDCCH.

Operations 800 begin with the UE receiving a first information from anaccess node regarding a QCL configuration for PDCCH (block 802). The QCLconfiguration for PDCCH includes a second information that a first RSfrom a first set of TCI states is spatially QCL'ed with a DMRS of PDCCH.The UE completes a beam failure recovery procedure (block 804). Part ofthe beam failure recovery procedure includes the UE selecting a new beamor receiving information about the new beam. The UE receives a frame ona PDCCH (block 806). The UE decodes the frame (block 808). The UEdecodes the frame by assuming that a DMRS of the PDCCH is not QCL'edwith the first RS from the first set of TCI states, for example.

In a second embodiment of the second example embodiment, a PDSCH framedecoding process, where a TCI field is present in a DCI that schedulesthe PDSCH, may be as follows:

-   -   A UE receives an information from an access node regarding        mapping between TCI states and TCI field in the DCI;    -   The UE detects a beam failure;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a first control frame (e.g., DCI) that schedules        a first data frame on a PDSCH, where the first control frame        includes a TCI field;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is not QCL'ed with an identified RS.

It is noted that the QCL configuration may be conveyed via RRC or RRCand MAC CE signaling. It is noted that the identified RS may beidentified by the TCI field. It is noted that the TCI field may be setto a predetermined value. The predetermined value may be set to zero.The predetermined value may be set to a maximum value that the TCI fieldis capable of representing, e.g., seven if the TCI field is three bitslong, three if the TCI field is two bits long, etc. The predeterminedvalue may be set to a value that no specific RS is mapped to in the TCIfield. As an example, if the length of the TCI field is 2 bits long,implying that there are 4 states that the TCI field is capable ofrepresenting. If there are only 2 states mapped to the TCI field, e.g.,state o and state 1, then states 2 and 3 may be the predeterminedvalues.

The PDSCH frame decoding process may also include:

-   -   The UE receives a signaling that updates a QCL configuration for        PDSCH, where the QCL configuration for PDSCH includes an        information that a second RS is included to a set of RSs that        the TCI field represents;    -   The UE receives a second control frame that schedules a second        data frame on a second PDSCH, where the second control frame        includes a TCI field;    -   The UE decodes the second data frame by assuming that a DMRS of        the PDSCH is QCL'ed with a second RS identified by the TCI        field.

The PDSCH frame decoding process may further include:

-   -   The BFRQ includes an information that a first RS is a new        candidate beam;    -   The first RS and the second RS are identical.

FIG. 8B illustrates a flow diagram of example operations 815 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame on a PDSCH, where a TCI field ispresent in a DCI that schedules the PDSCH.

Operations 815 begin with the UE receiving a mapping between TCI statesand a TCI field in the DCI (block 817). The UE completes a beam failurerecovery procedure (block 819). Part of the beam failure recoveryprocedure includes the UE selecting a new beam or receiving informationabout the new beam. The UE receives a first control frame that schedulesa first data frame on a PDSCH (block 821). The first control frame maybe a DCI. The first control frame may include a TCI field. The UEreceives and decodes the data frame (block 823). The UE decodes the dataframe by assuming that a DMRS of the PDSCH is not QCL'ed with a RSidentified by the TCI field, for example.

In a third embodiment of the second example embodiment, a PDSCH framedecoding process, where the TCI field is not present in a DCI thatschedules the PDSCH, may be as follows:

-   -   A UE determines a first RS that is QCL'ed with a DMRS for PDSCH        decoding;    -   The UE detects a beam failure;    -   The UE sends a BFRQ to the access node;    -   The UE receives a BFRP from the access node;    -   The UE receives a first data frame on a PDSCH;    -   The UE decodes the first data frame by assuming that a DMRS of        the PDSCH is not QCL'ed with the first RS.

FIG. 8C illustrates a flow diagram of example operations 830 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame on a PDSCH, where a TCI field is notpresent in a DCI that schedules the PDSCH.

Operations 830 begin with the UE determining a first RS that is QCL'edwith a DMRS for PDSCH decoding (block 832). The UE completes a beamfailure recovery procedure (block 834). Part of the beam failurerecovery procedure includes the UE selecting a new beam or receivinginformation about the new beam. The UE receives a first data frame on aPDSCH (block 836). The UE decodes the first data frame (block 838). TheUE decodes the first data frame by assuming that a DMRS of the PDSCH isnot QCL'ed with the first RS, for example.

In a fourth embodiment of the second example embodiment, a PDSCH framedecoding process, where the TCI field is present in a DCI that schedulesthe PDSCH, may be as follows:

-   -   A UE receives an information from an access node regarding a        mapping between TCI states and the TCI field in the DCI;    -   The UE receives a first control frame (e.g., DCI) that schedules        a first data frame on a PDSCH, where the first control frame        includes the TCI field;    -   If the TCI field is set to a first value, the UE decodes the        first data frame by assuming that a DMRS of the PDSCH is not        QCL'ed with an identified RS;    -   If the TCI field is set to a value other than the first value,        the UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with a RS identified by the TCI field.

In a fifth embodiment of the second example embodiment, a PDSCH framedecoding process, where the TCI field is present in a DCI that schedulesthe PDSCH, may be as follows:

-   -   A UE receives an information from an access node regarding a        mapping between TCI states and the TCI field in the DCI;    -   The UE receives a first control frame (e.g., DCI) that schedules        a first data frame on a PDSCH, where the first control frame        includes the TCI field;    -   If the TCI field is set to a first value, the UE decodes the        first data frame by assuming that a DMRS of the PDSCH is QCL'ed        with a DMRS of a PDCCH that carries the first control frame;    -   If the TCI field is set to a value other than the first value,        the UE decodes the first data frame by assuming that a DMRS of        the PDSCH is QCL'ed with a RS identified by the TCI field.

FIG. 8D illustrates a flow diagram of example operations 845 occurringin a UE participating in a beam failure detection, a beam failurerecovery, and a decoding of a frame on a PDSCH, where a TCI field ispresent in a DCI that schedules the PDSCH and preset values are used.

Operations 845 begin with the UE receiving a mapping between TCI statesand a TCI field in the DCI (block 847). The UE receives a first controlframe that schedules a first data frame on a PDSCH (block 849). Thefirst control frame may be a DCI. The first control frame may include aTCI field. The UE performs a check to determine if the TCI field is setto a first value (block 851). If the TCI field is set to the firstvalue, the UE decodes the first data frame by assuming that a DMRS ofthe PDSCH is not QCL'ed with a RS identified by the TCI field (block853). In another embodiment, if the TCI field is set to the first value,the UE decodes the first data frame by assuming that a DMRS of the PDSCHis QCL'ed with a DMRS of a PDCCH that carries the first control frame.If the TCI field is not set to the first value, the UE decodes the firstdata frame by assuming that a DMRS of the PDSCH is QCL'ed with a RSidentified by the TCI field (block 854).

FIG. 9 illustrates an example communication system 900. In general, thesystem 900 enables multiple wireless or wired users to transmit andreceive data and other content. The system 900 may implement one or morechannel access methods, such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), ornon-orthogonal multiple access (NOMA).

In this example, the communication system 900 includes electronicdevices (ED) 910 a-910 c, radio access networks (RANs) 920 a-920 b, acore network 930, a public switched telephone network (PSTN) 940, theInternet 950, and other networks 960. While certain numbers of thesecomponents or elements are shown in FIG. 9 , any number of thesecomponents or elements may be included in the system 900.

The EDs 910 a-910 c are configured to operate or communicate in thesystem 900. For example, the EDs 910 a-910 c are configured to transmitor receive via wireless or wired communication channels. Each ED 910a-910 c represents any suitable end user device and may include suchdevices (or may be referred to) as a user equipment or device (UE),wireless transmit or receive unit (WTRU), mobile station, fixed ormobile subscriber unit, cellular telephone, personal digital assistant(PDA), smartphone, laptop, computer, touchpad, wireless sensor, orconsumer electronics device.

The RANs 920 a-920 b here include base stations 970 a-970 b,respectively. Each base station 970 a-970 b is configured to wirelesslyinterface with one or more of the EDs 910 a-910 c to enable access tothe core network 930, the PSTN 940, the Internet 950, or the othernetworks 960. For example, the base stations 970 a-970 b may include (orbe) one or more of several well-known devices, such as a basetransceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNodeB),a Home NodeB, a Home eNodeB, a site controller, an access point (AP), ora wireless router. The EDs 910 a-910 c are configured to interface andcommunicate with the Internet 950 and may access the core network 930,the PSTN 940, or the other networks 960.

In the embodiment shown in FIG. 9 , the base station 970 a forms part ofthe RAN 920 a, which may include other base stations, elements, ordevices. Also, the base station 970 b forms part of the RAN 920 b, whichmay include other base stations, elements, or devices. Each base station970 a-970 b operates to transmit or receive wireless signals within aparticular geographic region or area, sometimes referred to as a “cell.”In some embodiments, multiple-input multiple-output (MIMO) technologymay be employed having multiple transceivers for each cell.

The base stations 970 a-970 b communicate with one or more of the EDs910 a-910 c over one or more air interfaces 990 using wirelesscommunication links. The air interfaces 990 may utilize any suitableradio access technology.

It is contemplated that the system 900 may use multiple channel accessfunctionality, including such schemes as described above. In particularembodiments, the base stations and EDs implement LTE, LTE-A, or LTE-B.Of course, other multiple access schemes and wireless protocols may beutilized.

The RANs 920 a-920 b are in communication with the core network 930 toprovide the EDs 910 a-910 c with voice, data, application, Voice overInternet Protocol (VoIP), or other services. Understandably, the RANs920 a-920 b or the core network 930 may be in direct or indirectcommunication with one or more other RANs (not shown). The core network930 may also serve as a gateway access for other networks (such as thePSTN 940, the Internet 950, and the other networks 960). In addition,some or all of the EDs 910 a-910 c may include functionality forcommunicating with different wireless networks over different wirelesslinks using different wireless technologies or protocols. Instead ofwireless communication (or in addition thereto), the EDs may communicatevia wired communication channels to a service provider or switch (notshown), and to the Internet 950.

Although FIG. 9 illustrates one example of a communication system,various changes may be made to FIG. 9 . For example, the communicationsystem 900 could include any number of EDs, base stations, networks, orother components in any suitable configuration.

FIGS. 10A and 10B illustrate example devices that may implement themethods and teachings according to this disclosure. In particular, FIG.10A illustrates an example ED 1010, and FIG. 10B illustrates an examplebase station 1070. These components could be used in the system 900 orin any other suitable system.

As shown in FIG. 10A, the ED 1010 includes at least one processing unit1000. The processing unit 1000 implements various processing operationsof the ED 1010. For example, the processing unit 1000 could performsignal coding, data processing, power control, input/output processing,or any other functionality enabling the ED 1010 to operate in the system900. The processing unit 1000 also supports the methods and teachingsdescribed in more detail above. Each processing unit 1000 includes anysuitable processing or computing device configured to perform one ormore operations. Each processing unit 1000 could, for example, include amicroprocessor, microcontroller, digital signal processor, fieldprogrammable gate array, or application specific integrated circuit.

The ED 1010 also includes at least one transceiver 1002. The transceiver1002 is configured to modulate data or other content for transmission byat least one antenna or NIC (Network Interface Controller) 1004. Thetransceiver 1002 is also configured to demodulate data or other contentreceived by the at least one antenna 1004. Each transceiver 1002includes any suitable structure for generating signals for wireless orwired transmission or processing signals received wirelessly or by wire.Each antenna 1004 includes any suitable structure for transmitting orreceiving wireless or wired signals. One or multiple transceivers 1002could be used in the ED 1010, and one or multiple antennas 1004 could beused in the ED 1010. Although shown as a single functional unit, atransceiver 1002 could also be implemented using at least onetransmitter and at least one separate receiver.

The ED 1010 further includes one or more input/output devices 1006 orinterfaces (such as a wired interface to the Internet 950). Theinput/output devices 1006 facilitate interaction with a user or otherdevices (network communications) in the network. Each input/outputdevice 1006 includes any suitable structure for providing information toor receiving or providing information from a user, such as a speaker,microphone, keypad, keyboard, display, or touch screen, includingnetwork interface communications.

In addition, the ED 1010 includes at least one memory 1008. The memory1008 stores instructions and data used, generated, or collected by theED 1010. For example, the memory 1008 could store software or firmwareinstructions executed by the processing unit(s) 1000 and data used toreduce or eliminate interference in incoming signals. Each memory 1008includes any suitable volatile or non-volatile storage and retrievaldevice(s). Any suitable type of memory may be used, such as randomaccess memory (RAM), read only memory (ROM), hard disk, optical disc,subscriber identity module (SIM) card, memory stick, secure digital (SD)memory card, and the like.

As shown in FIG. 10B, the base station 1070 includes at least oneprocessing unit 1050, at least one transceiver 1052, which includesfunctionality for a transmitter and a receiver, one or more antennas1056, at least one memory 1058, and one or more input/output devices orinterfaces 1066. A scheduler, which would be understood by one skilledin the art, is coupled to the processing unit 1050. The scheduler couldbe included within or operated separately from the base station 1070.The processing unit 1050 implements various processing operations of thebase station 1070, such as signal coding, data processing, powercontrol, input/output processing, or any other functionality. Theprocessing unit 1050 can also support the methods and teachingsdescribed in more detail above. Each processing unit 1050 includes anysuitable processing or computing device configured to perform one ormore operations. Each processing unit 1050 could, for example, include amicroprocessor, microcontroller, digital signal processor, fieldprogrammable gate array, or application specific integrated circuit.

Each transceiver 1052 includes any suitable structure for generatingsignals for wireless or wired transmission to one or more EDs or otherdevices. Each transceiver 1052 further includes any suitable structurefor processing signals received wirelessly or by wire from one or moreEDs or other devices. Although shown combined as a transceiver 1052, atransmitter and a receiver could be separate components. Each antenna1056 includes any suitable structure for transmitting or receivingwireless or wired signals. While a common antenna 1056 is shown here asbeing coupled to the transceiver 1052, one or more antennas 1056 couldbe coupled to the transceiver(s) 1052, allowing separate antennas 1056to be coupled to the transmitter and the receiver if equipped asseparate components. Each memory 1058 includes any suitable volatile ornon-volatile storage and retrieval device(s). Each input/output device1066 facilitates interaction with a user or other devices (networkcommunications) in the network. Each input/output device 1066 includesany suitable structure for providing information to or receiving orproviding information from a user, including network interfacecommunications.

FIG. 11 is a block diagram of a computing system 1100 that may be usedfor implementing the devices and methods disclosed herein. For example,the computing system can be any entity of UE, access network (AN),mobility management (MM), session management (SM), user plane gateway(UPGW), or access stratum (AS). Specific devices may utilize all of thecomponents shown or only a subset of the components, and levels ofintegration may vary from device to device. Furthermore, a device maycontain multiple instances of a component, such as multiple processingunits, processors, memories, transmitters, receivers, etc. The computingsystem 1100 includes a processing unit 1102. The processing unitincludes a central processing unit (CPU) 1114, memory 1108, and mayfurther include a mass storage device 1104, a video adapter 1110, and anI/O interface 1112 connected to a bus 1120.

The bus 1120 may be one or more of any type of several bus architecturesincluding a memory bus or memory controller, a peripheral bus, or avideo bus. The CPU 1114 may comprise any type of electronic dataprocessor. The memory 1108 may comprise any type of non-transitorysystem memory such as static random access memory (SRAM), dynamic randomaccess memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM),or a combination thereof. In an embodiment, the memory 1108 may includeROM for use at boot-up, and DRAM for program and data storage for usewhile executing programs.

The mass storage 1104 may comprise any type of non-transitory storagedevice configured to store data, programs, and other information and tomake the data, programs, and other information accessible via the bus1120. The mass storage 1104 may comprise, for example, one or more of asolid state drive, hard disk drive, a magnetic disk drive, or an opticaldisk drive.

The video adapter 1110 and the I/O interface 1112 provide interfaces tocouple external input and output devices to the processing unit 1102. Asillustrated, examples of input and output devices include a display 1118coupled to the video adapter 1110 and a mouse, keyboard, or printer 1116coupled to the I/O interface 1112. Other devices may be coupled to theprocessing unit 1102, and additional or fewer interface cards may beutilized. For example, a serial interface such as Universal Serial Bus(USB) (not shown) may be used to provide an interface for an externaldevice.

The processing unit 1102 also includes one or more network interfaces1106, which may comprise wired links, such as an Ethernet cable, orwireless links to access nodes or different networks. The networkinterfaces 1106 allow the processing unit 1102 to communicate withremote units via the networks. For example, the network interfaces 1106may provide wireless communication via one or more transmitters ortransmit antennas and one or more receivers or receive antennas. In anembodiment, the processing unit 1102 is coupled to a local-area network1122 or a wide-area network for data processing and communications withremote devices, such as other processing units, the Internet, or remotestorage facilities.

It should be appreciated that one or more steps of the embodimentmethods provided herein may be performed by corresponding units ormodules. For example, a signal may be transmitted by a transmitting unitor a transmitting module. A signal may be received by a receiving unitor a receiving module. A signal may be processed by a processing unit ora processing module. Other steps may be performed by a decoding unit ormodule. The respective units or modules may be hardware, software, or acombination thereof. For instance, one or more of the units or modulesmay be an integrated circuit, such as field programmable gate arrays(FPGAs) or application-specific integrated circuits (ASICs).

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims.

What is claimed is:
 1. A method, comprising: receiving, by an accessnode from a user equipment (UE), a beam failure recovery request (BFRQ)for initiating a beam failure recovery, the BFRQ indicating a firstreference signal selected by the UE, the first reference signalcorresponding to a new beam; transmitting, by the access node, aresponse to the BFRQ based on a first quasi co-located (QCL)relationship between the first reference signal and a second referencesignal, the first reference signal corresponding to the new beam, andthe second reference signal being a demodulation reference signal (DMRS)of a physical downlink control channel (PDCCH) for transmitting theresponse; and transmitting, by the access node, a transmission on thePDCCH or a physical downlink shared channel (PDSCH) based on a secondQCL relationship between the first reference signal and a thirdreference signal, the third reference signal being the DMRS of the PDCCHor a DMRS of the PDSCH.
 2. The method of claim 1, wherein the methodfurther comprises: transmitting, by the access node, downlink controlinformation (DCI) for scheduling the PDSCH.
 3. The method of claim 1,wherein the method further comprises: using, by the access node, anupdated QCL relationship between a fourth reference signal and the DMRSof the PDCCH or the DMRS of the PDSCH for transmitting PDSCH data orPDCCH data to the UE, the fourth reference signal corresponding to afirst beam.
 4. The method of claim 3, wherein the first beam is the newbeam selected by the UE.
 5. The method of claim 3, wherein the firstbeam is another beam different from the new beam selected by the UE. 6.The method of claim 3, the updated QCL relationship being a transmissionconfiguration indication (TCI) state.
 7. The method of claim 6, the TCIstate being carried in a higher layer message.
 8. The method of claim 1,the transmitting the transmission on the PDCCH or the PDSCH comprising:transmitting the transmission on the PDCCH or the PDSCH before anyupdated QCL configuration responsive to the BFRQ is sent.
 9. An accessnode comprising: at least one processor; and a non-transitory computerreadable storage medium storing programming for execution by the atleast one processor, the programming including instructions to cause theaccess node to perform operations including: receiving, from a userequipment (UE), a beam failure recovery request (BFRQ) for initiating abeam failure recovery, the BFRQ indicating a first reference signalselected by the UE, the first reference signal corresponding to a newbeam; transmitting a response to the BFRQ based on a first quasico-located (QCL) relationship between the first reference signal and asecond reference signal, the first reference signal corresponding to thenew beam, and the second reference signal being a demodulation referencesignal (DMRS) of a physical downlink control channel (PDCCH) fortransmitting the response; and transmitting a transmission on the PDCCHor a physical downlink shared channel (PDSCH) based on a second QCLrelationship between the first reference signal and a third referencesignal, the third reference signal being the DMRS of the PDCCH or a DMRSof the PDSCH.
 10. The access node of claim 9, the operations furthercomprising: transmitting downlink control information (DCI) forscheduling the PDSCH.
 11. The access node of claim 9, the operationsfurther comprising: using an updated QCL relationship between a fourthreference signal and the DMRS of the PDCCH or the DMRS of the PDSCH fortransmitting PDSCH data or PDCCH data to the UE, the fourth referencesignal corresponding to a first beam.
 12. The access node of claim ii,wherein the first beam is the new beam selected by the UE.
 13. Theaccess node of claim ii, wherein the first beam is another beamdifferent from the new beam selected by the UE.
 14. The access node ofclaim ii, the updated QCL relationship being a transmissionconfiguration indication (TCI) state.
 15. The access node of claim 14,the TCI state being carried in a higher layer message.
 16. The accessnode of claim 9, the transmitting the transmission on the PDCCH or thePDSCH comprising: transmitting the transmission on the PDCCH or thePDSCH before any updated QCL configuration responsive to the BFRQ issent.
 17. A non-transitory storage medium comprising a program that,when executed by an access node, causes the access node to performoperations including: receiving, from a user equipment (UE), a beamfailure recovery request (BFRQ) for initiating a beam failure recovery,the BFRQ indicating a first reference signal selected by the UE, thefirst reference signal corresponding to a new beam; transmitting aresponse to the BFRQ based on a first quasi co-located (QCL)relationship between the first reference signal and a second referencesignal, the first reference signal corresponding to the new beamselected by the UE, and the second reference signal being a demodulationreference signal (DMRS) of a physical downlink control channel (PDCCH)for transmitting the response; and transmitting a transmission on thePDCCH or a physical downlink shared channel (PDSCH) based on a secondQCL relationship between the first reference signal and a thirdreference signal, the third reference signal being the DMRS of the PDCCHor a DMRS of the PDSCH.
 18. The non-transitory storage medium of claim17, the operations further comprising: transmitting, by the access node,downlink control information (DCI) for scheduling the PDSCH.
 19. Thenon-transitory storage medium of claim 17, the operations furthercomprising: using an updated QCL relationship between a fourth referencesignal and the DMRS of the PDCCH or the DMRS of the PDSCH fortransmitting PDSCH data or PDCCH data to the UE, the fourth referencesignal corresponding to a first beam.
 20. The non-transitory storagemedium of claim 19, wherein the first beam is the new beam selected bythe UE.
 21. The non-transitory storage medium of claim 19, wherein thefirst beam is another beam different from the new beam selected by theUE.
 22. The non-transitory storage medium of claim 19, the updated QCLrelationship being a transmission configuration indication (TCI) state.23. The non-transitory storage medium of claim 22, the TCI state beingcarried in a higher layer message.
 24. The non-transitory storage mediumof claim 17, the transmitting the transmission on the PDCCH or the PDSCHcomprising: transmitting the transmission on the PDCCH or the PDSCHbefore any updated QCL configuration responsive to the BFRQ is sent.